Today, espresso is brewed by forcing hot, not boiling, water under high pressure through powdery fine coffee. The process is called “pulling” a shot, which has to do with early machines that had a pull lever to begin the brewing process; today, most machines have a simple button. The ground coffee is packed into a metal filter basket with 7-10 grams of grounds for a single shot, and 12-18 grams for double. The grounds are pressed down to form a firm puck of coffee. Pressurized water is then forced through the coffee in the portafilter which deposits the resulting espresso into a shot glass or demitasse (white porcelain espresso cup). Brewing takes under thirty seconds. The espresso, which is a chemically complex drink and will degrade quickly with heat loss, is to be served immediately at a temperature of 165 degrees Fahrenheit.
We pride ourselves on our espresso blends, because making good espresso, even from a programmable machine, can be a challenge due to espresso’s volatile and complex nature. Properly brewed espresso has three parts, the heart, body, and crema (crema is the lighter reddish foam that floats on the surface); when a glass is brewed, all three parts should be seen as three different layers. When consumed, the espresso should have a fine aroma, rich body, and a balanced bitter-sweet taste with a hint of acidity. The espresso flavor and consistency are easily affected by minor problems such as the over or under grinding of beans, over pressing of grounds into the metal filter, and by fluctuation in water temperature. Over and under grinding affect the appearance of crema, as does the firmness of the ground coffee puck in the portafilter. Too much pressure in packing the coffee grounds plus a too-fine grind will cause the pressurized water to stay in the filter too long, resulting in very little crema. If the crema is tan instead of reddish, it may indicate that the grounds are packed too lightly, and the water has run through too quickly. Water that is too cold during brewing can cause sourness, while too hot water can cause bitterness.